This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Hemocyanins (HC), the blue copper-containing oxygen-transporting proteins of many arthropods and molluscs can be activated by SDS or enzymatic cleavage to exert an enzymatic phenoloxidase activity;thereby mimicking the activity of tyrosinases (Ty) or catecholoxidases (CO). Our collaborators proposed that the first domain of a hemocyanin subunit shields the active site entrance and is tilted, disordered or cleaved upon activation in hemocyanin, opening an entrance for the substrates. This mechanism should be the same in the case of tyrosinase from arthropods, which have the same quaternary structure as hemocyanins.